Who first used the term "enzyme"?

Hydrolytic enzymes that function at low $pH$ are called .........

Which protein is found in the maximum amount in the biosphere?

The following reaction depicts the activity of a particular class of enzymes:
$X-Y$ attached to $C-C$ (Substrate) $\xrightarrow{E}$ $X-Y$ + $C=C$ (Product)
Identify the enzyme class '$E$' from the following options:

All enzymes are composed of which of the following?

Enzymes are primarily which type of proteins?